4. 1) 2) 3) 4)

Решение:

1. \( 28 \frac{4}{5} : 13 \frac{5}{7} + 6 \frac{3}{5} : \frac{2}{3} = \frac{144}{5} : \frac{96}{7} + \frac{33}{5} : \frac{2}{3} = \frac{144}{5} \cdot \frac{7}{96} + \frac{33}{5} \cdot \frac{3}{2} = \frac{3 \cdot 7}{5 \cdot 2} + \frac{99}{10} = \frac{21}{10} + \frac{99}{10} = \frac{120}{10} = 12 \)
2. \( 1 \frac{11}{16} : 2 \frac{1}{4} = \frac{27}{16} : \frac{9}{4} = \frac{27}{16} \cdot \frac{4}{9} = \frac{3}{4} \)
3. \( \frac{1}{2} + 2 \frac{2}{3} + 3 \frac{3}{4} = \frac{1 \cdot 6 + 2 \cdot 12 + 3 \cdot 9}{12} = \frac{6 + 24 + 27}{12} = \frac{57}{12} = \frac{19}{4} = 4 \frac{3}{4} \)
4. \( 14 - 15 \frac{1}{8} : 2 \frac{1}{5} = 14 - \frac{121}{8} : \frac{11}{5} = 14 - \frac{121}{8} \cdot \frac{5}{11} = 14 - \frac{11 \cdot 5}{8} = 14 - \frac{55}{8} = \frac{112 - 55}{8} = \frac{57}{8} = 7 \frac{1}{8} \)

Ответ: 1) 12; 2) \( \frac{3}{4} \); 3) \( 4 \frac{3}{4} \); 4) \( 7 \frac{1}{8} \).